RPA 7 Chromotography

Question 1

Steps

Answer 1

• pencil to draw horizontal line across chromatography paper
• mark 5 pencil slots along line
• use capillary tube to put small spot of known food colours and unknown onto pencil spots
• pour water into beaker at 1cm
• attach paper to glass rod using tape and lower paper into beaker
• bottom of paper should dip into paper

Question 2

Importance of small spots

Answer 2

Prevents colours from spreading into each other later

Question 3

How to measure chemical in the colour

Answer 3

• measure distance from pencil line to centre of each spot
• measure distance moved by water from pencil line
• distance moved by chemical divided by distance moved by solvent
• look up the Rf in database and identify the chemical

Question 4

What happens to dots

Answer 4

Solvents moves up paper and dissolved ink in coloured dots

Question 5

Describe paper

Answer 5

Stationary stage
= doesn’t move

Question 6

Describe solvent

Answer 6

Mobile phase
= solvent moves

Question 7

Describe results of a pure compound

Answer 7

Produce a single spot in all solvents

Question 8

Rf formula

Answer 8

Distance moved by substance/ distance moved by solvent